A medicament in liquid form is commonly delivered into a patient through a needle. A dispenser such as a syringe may be used to deliver the medicament through the needle. The syringe is often connected to the needle by a connector. The syringe, connector and needle form a pathway for delivery of the medicament. Some of the medicament may leave the pathway and enter into void space in the connector and thus not be delivered to the patient. Often, the void space is small relative to the volume of medicament that is to be delivered. In such cases, the therapeutic and economic consequences of losing medicament from the pathway may be acceptable. Sometimes, however, the loss is not acceptable. For example, the void space may be large relative to the volume of medicament that is to be delivered, the medicament may be expensive, the loss may make dosing unpredictable because the loss may vary in volume from one connector to another, among other reasons.
It would be desirable, therefore, to provide apparatus and methods for reducing the loss of medicament from the delivery pathway.
Dispensers such as syringes are often prefilled with a desired medicament volume. A practitioner then fully depresses a plunger in the syringe to deliver the medicament into the patient. Prefilling the syringe reduces the likelihood of overfilling or underfilling by a practitioner. Fully depressing the plunger of the syringe reduces the likelihood of underdosing the patient, assuming that the prefilled volume is correct.
Volumetric precision of prefilling a large volume may be greater than the volumetric precision of prefilling a small volume. When it is desirable to prefill the dispenser for the delivery of a small volume, the lack of volumetric precision may be unacceptable. It would be desirable, therefore, to provide apparatus and methods for using a dispenser to deliver a small volume of the medicament to the patient.